Eating these three autumn foods carries some risk

With brightly coloured leaves lying in thick carpets on the ground, autumn produce is now abundant on fruit and vegetable shelves in supermarkets nationwide.

But while many indulge in seasonal comfort foods such as potatoes, onions, apples and grapes, some autumn produce needs to be eaten in moderation, experts say.

Without getting caught up in the virtues of gouging on the endless supply of feijoas that can be found in offices at this time of year, here are three autumn foods that have some noteworthy side-effects to be aware of.

Pumpkin

From late summer, fresh pumpkin starts to appear in piles on tables at markets nationwide.

As a long-lasting crop, pumpkin can be enjoyed throughout the autumn and winter months.

Pumpkins are usually fully mature in autumn, offering a sweeter flavour and richer nutrients, making them perfect for seasonal dishes such as pumpkin soup, roast pumpkin and pumpkin pie.

New Zealand's warm climate and long summer daylight hours provide ideal conditions for pumpkin to grow, expand and ripen.

Pumpkin is mostly regarded as being beneficial for gut health.

However, the vegetable contains large amounts of fibre and so eating too much can cause stomach cramps, bloating or constipation for some people.

To prevent stomach pain, dieticians suggest that older adults or those with digestive issues should enjoy it in moderation.

Pumpkins may come into contact with bacteria, viruses and other microorganisms during planting, harvesting and transportation, and so the winter squash should always be washed and cooked thoroughly before eating.

Some nutrients in pumpkin may have a mild diuretic effect, which might affect the way in which certain medications are absorbed or metabolized.

Anyone taking prescription medication is advised to talk to their doctor before making major dietary changes, medical experts say.

It is best to store pumpkin in a dry, cool and well-ventilated place. Avoid storing pumpkin in humid conditions to prevent mould and spoilage.

Persimmon

Originating from China thousands of years ago, persimmon was cultivated in East Asia before spreading to South Asia, the Americas and Europe.

The fruit has been grown in New Zealand since the 1870s.

Crops are typically harvested from around mid-May to June, with some varieties available from April to August.

Persimmon cultivation in New Zealand primarily takes place in the warmer regions of the north, including Auckland and Gisborne, although the fruit has also been found in other parts of the country.

New Zealanders have historically cultivated bitter varieties of persimmon that contain a high level of tannins, with consumers needing to wait until the fruit is very ripe for it to become sweet and edible.

About 90 percent of persimmon cultivated in China are of the bitter variety.

Many Chinese households historically soaked the fruit in water flavoured with lime juice or ripened in the same basket as lime for several days to remove the bitterness.

A sweeter tomato-shaped variety of persimmon has been available in New Zealand since the 1980s.

Interestingly, New Zealand has recently started to export this variety to China.

Persimmon offers numerous health benefits and are rich in vitamins A and C and dietary fibre as well as minerals such as potassium, manganese and copper.

However, dieticians recommend consuming only one or two persimmon per day, while those with known allergies should avoid them altogether.

They advise consumers to avoid consuming unripe persimmon as well as eating it in excess or on an empty stomach.

The caution surrounding persimmon consumption stems from soluble tannins found in the fruit.

The tannins - shibuol in particular - can react with proteins under the influence of gastric acid to form indigestible material in the gastrointestinal tract.

When combined with dietary fibre, pectin and other substances in the stomach, the material can develop into a diospyrobezoar (a phytobezoar, or plant-based mass, specifically formed from persimmons).

Oxalates found in persimmon may also increase the risk of a person developing kidney stones.

The tannin found in the fruit can affect the absorption of minerals such as calcium, which may indirectly promote the formation of calcium oxalate stones, especially when consumed in large quantities or with insufficient water intake.

Dieticians typically recommend observing the following when consuming persimmon:

• Refrain from consuming large quantities of unripe persimmon on an empty stomach. It is also advisable to moderate their intake when combined with high-protein food.
• Peel persimmon before consuming it, as tannins tend to be concentrated in the skin and outer flesh of the fruit.
• Eat ripe persimmon, which contains lower tannin content.
• Avoid eating persimmon on an empty stomach, as high gastric acid levels may increase the risk of plant-based masses developing in the gastrointestinal tract.
• Limit consumption to one or two medium-sized persimmons per day.

LI] Chew persimmon thoroughly before swallowing. Individuals who have difficulty chewing or are showing signs of digestive problems are advised to avoid swallowing large pieces of the fruit.

• Consume persimmon in moderation or avoid the fruit altogether if you have a history of kidney stones.

Chestnut

China is one of the largest exporters of chestnuts worldwide, according to data compiled by the Observatory of Economic Complexity.

New Zealand doesn't trade chestnuts at the same volume, but exported chestnuts from the South Pacific nation are renowned for their size and quality.

Chestnuts are difficult to store for long periods of time because they're full of moisture, which makes them go bad much faster than dry nuts like almond or walnut.

Indeed, households typically freeze chestnuts - either raw or cooked - to keep them fresh for longer. Once thawed, it's best to eat them right away.

If kept in a refrigerator, fresh chestnuts typically last about two or three weeks.

Consumers are advised to be aware of some risks associated with eating chestnuts.

They contain high levels of starch and fibre, so eating too many can cause bloating or indigestion.

Chestnuts also contain a surprising amount of carbohydrates and while they are healthier than refined sugar, they still have a moderate glycaemic index. As such, diabetics are advised to refrain from consuming an excessive amount.

In China, ancient folklore says people should refrain from eating chestnuts in large quantities with high-protein foods such as crab.

While there is no strong scientific evidence to support this, excessive consumption of high-fibre or high-protein foods can cause digestive discomfort for individuals with sensitive gastrointestinal systems.